1. Field of the Invention
The invention relates to a hybrid resin, which is suitable in particular for impregnating paper webs. The hybrid resin according to the invention can be used advantageously for improving the mechanical properties of counteracting layers in multilayer boards.
2. Discussion of Background Information
It is known to coat wood materials such as chipboards, fiberboards, for example, MDF boards (medium density fiberboard) or HDF boards (high density fiberboard) or OSB boards (oriented structural board) with decorative papers, which are preferably impregnated with amino resins. Furthermore, it is known to coat continuous pressure laminates (CPL), which are formed by laying several paper layers on top of one another, with decorative papers, which are preferably impregnated with amino resins. The decorative papers used for this purpose generally have a weight per unit area of 30-140 g/m2. Usually, the resins used for impregnating the paper webs are polycondensation products of melamine with formaldehyde. However, polycondensation products are also used, which have a mixed polycondensation of urea and/or melamine with formaldehyde.
To compensate for the pulling effect exerted on the material board by the layer impregnated with resin, usually a counteracting layer is applied to the opposite side of the material board. Melamine formaldehyde resins, for example, are used as standard impregnation for conventional counteracting layer impregnants. However, these resins are expensive, so that alternatives are sought.
Melamine urea formaldehyde resins are used in various fields, for example, for waterproof gluing of wood materials or for the core impregnation of decorative papers. Compared to pure melamine resins, they have economic advantages in particular. However, in various areas they cannot replace pure melamine formaldehyde resins, since the mechanical and chemical properties of MUF resins are poorer in a direct comparison and thus are disadvantageous. For example, MUF resins do not develop the necessary pulling effect to produce counteracting impregnants for laminate floors in order to balance out the melamine surface with the same use of materials. Accordingly, either pure melamine formaldehyde resins were used as counteracting impregnants, or if MUF resins were used, very large amounts of resin were necessary, which has technical as well as economic disadvantages.